girls advice needed /// please comment

hi girls
there was a girl in my class couple of years back. being an introvert person, talk less with girls, but she had a good impression, like being close to ideal girl (confident, caring, intellegent n it was like she wont get into relationship till marriage). after almost a year (last year) she contacted me for some reason, numbers exchanged and we talk on whatsapp then, initially started with exchanging funny pics/vids but later we share a lot like every single detail every day. any change in dp/status is noticed n she said she like and comments on it. its like if one day passed and we didnt talk then she initiates the conversation. i like her and when i try to make my mind to propose i always think she would say that i crossed my line. because when sometime i tease her about any relationship, she always reply she love being independent, which makes me to stop.

but from last month she isnt replying like before. when i initiates conversation, she answers only that question, just hello hi. so i just want to know what is going on her minds because girls know each other better, much more than me.

help will be appreciated.
thanks in advance